Tension screen



NOV. 18, 1952 J, m E 2,618,332

TENSION SCREEN Filed Oct. 22, .1951

BY WWW w zg gzwv Patented Nov. 18, 1952 TENSION SCREEN Jacob M. Gwynne,Coral Gables, Fla. Application October 22, 1951, Serial No. 252,446

2 Claims.

This invention relates to window screens, and particularly to screens ofthe tension type in which no rigid frame is employed for the screen,which is suspended between the head and sill of a window opening andkept taut by being placed under tension. I

A general object of the invention is to provide a tension screen ofsuperior design and construction, relatively small cost, and one whichis capable of being securely fastened in place in such manner that therisk of inadvertent loosening or displacement is substantiallyeliminated Another object of the invention is the provision foradjustment for wide tolerances in the plumb and level and height of thewindow opening by varying the height of the angle screw supports at bothtop and bottom of the screen.

Another object of the invention is the provision of a window screen ofthe character described, including special cam-type locking devices forplacing the screen under tension easily, each said device comprisingfixed locking means secured to the sill of the window and a cooperatinglocking cam pivoted on a rigid member disposed along the lower edge ofthe screen, for engagement with the fixed locking means. The fixedlocking means or angle screw is adjustable in height to take care ofvariance in length of screen or window, but is fixed as a locking deviceas soon as the number of turns inserted in sill for good tension hasbeen determined by test.

The cam surface of the said pivoted cam comprises an entering portionhaving a geometrically decreasing rate of rise until it reaches thelooking portion where the increase in rise is zero, whereby when thesaid locking portion is engaged with the fixed locking means, there isno turning moment in either direction exerted on the pivoted cam, or inother words, the forces acting between the cam and the locking means areexactly vertical. Inasmuch as this geometrical decrease in rate of riseon the cam is inversely proportional to the build-up of tension in thescreen as it is being locked, the design not only provides easy lockingand unlocking with a minimum of friction, but provides a stable lockthat will not vibrate loose. The latter condition is due to theadditional fact that the point of zero rate of rise on the cam is also(when the cam is in looking position only) the only point of tangency orcontact between the cam and the locking device that is also on thevertical line of tension between the top screen screw support, thebottom (or looking) angle screw support, and the pivot point of the cam.

- Other and further objects, features and advantages will be apparentfrom the description which follows, read in connection with theaccompanying drawings in which Figure 1 is an elevational view, lookingfrom the inside of the building, of a window frame provided with thescreen according to the present invention;

Figure 2 is a transverse vertical section on line 2-2 of Figure 1;

Figure 3 is a perspective view, on an enlarged scale, of the left-handportion of the screen shown in Figure 1; and

Figure 4 is an enlarged detail view illustrating the curvature of thecam surface.

In order to facilitate an understanding of the invention, reference ismade to the embodiment thereof shown in the accompanying drawings anddetailed description language is employed. It will nevertheless beunderstood that no limitation of the invention is thereby intended andthat .various changes and alterations are contemplated such as wouldordinarily occur to one skilled in the art to which the inventionrelates.

Referring now to the drawings, the window frame illustrated in Figure lis of conventional construction comprising a sill Iil, jambs H and I2,and head [3. Each of the jambs H and I2 and the head [3 are providedwith inwardly extending sash stops It against the outer side of whichthe screen is adapted to be seated. The

. sash stop I 4 is the outer'member defining the guide or groove inwhich the outer and upper sash of a double-hung window is slidable. Forpurposes of clarity, no sash is shown in the drawings.

The upper surface of the sill 10, as best seen in Figure 2, is rabbetedto provide a vertical shoulder l5 against which the lower edge of thescreen is adapted to seat, that portion of the upper sill surface lyingoutwardly thereof and identified by the numeral I5 being preferablyslightly inclined downwardly and outwardly to facilitate drainage ofatmospheric moisture therefrom. The construction thus far described isconventional, and not a part of the invention. It may be fabricated ofwood, metal, or other suitable material. The screen of the presentinvention comprises generally the sheet 20 of square or rectangular meshmaterial, such as steel, bronze or aluminum screen wire, or square orrectangular mesh screen material fabricated of plastic filaments, suchmaterial being in common formed with a groove 23 adjacent its loweredge, and into which the upper edge of the sheet is tightly jammed bymeans of a spline 24. The sill channel 22 is similarly formed with agroove 25 adjacent its upper edge in which the lower edge of the sheet20 is fastened by means of a spline 26 The channels 2| and 22 andsplines 24 and 26 may be madeof any suitable material, being fabricatedpreferably of light non-corrosive material such as aluminum or sheetbronze.

The head channel 2| is provided with spaced apertures 21 for engagingsimilarly spaced angle screws 28 anchored in the sash stop M of head |3of the window frame, the transverse portions, of the angle screws 28being slightly inclined downwardly and inwardly, as best seen iniFigure2, to insure that the screen, when pulled .down.-

wardly, is thus biased inwardly to fit "firmly vides some measure ofprotection'against entry of atmospheric moisture under the lower end ofthe extension 30. Thesliding engagement between the extension member 30and the sill channe1'22 permits accommodation of the latter toinequalities in the vertical width of the shoulder 15, from its one endto the other-but, more importantly, permits adjustment of the overalllength of the screen to accommodate-minor variati'ons, from standard, inthe height of the window opening.

"Toward either end of the sill c'hannel'22, and preferably locateddirectly beneath thesupporting hooks 28, are secured cam 'members 35,mounted on pivots 3-6. Thelatter may'c'onven ien-tly 'comprise'headedbolts or rivets fll'tightly' secured to th ill channel 22 by'means ofnuts of a sheet metal stamping, or the like,'andis formed with aturned-over handle portion 4| :for

ease in manipulation. Thenose or operative portion of the cam, isprovided with an'upper or camm'ing surface 43 which engages hooks '42anchored in the sill 0 at'points directly beneath thehooks28'.

'The character of theprofiie of the camming surface '43 is a particularfeature .of the present invention, and comprises an entering portionhaving a geometrically decreasing rate'o'f riseindioated at 43c until itreaches the locking portion of the cam w'herethe increase rise is zeroas indicated at 43b. The curve 43 'is'an'arcofa circle whose center lieson the vertical line oining" the top and bottom 'supporthoo'ks'ifland42, respectively, and the cam pivot, the-distance of the'cent'er of suchare above-'thepivot'point of the cam being chosen so as to give the mmthe proper amount of travel"to apply the-desired degree of tension tothe screen. Since the radius of said are is different from Gouger thamthe pivot radius of the :cam, there will be only cam position in whichthe cam surface will contact the hook 42 at a point which is exactly onthe aforesaid vertical line, such position being the locking positiondefined above, and preferably the cam is so formed that when it occupiesthe defined locking position, the handle portion 4| is exactlyhorizontal.

When the cam is in lockingposition, the forces acting between the camand hook will be exactly vertical, with no resulting torque acting onthe cam and tending to cause its inadvertent disengagement. Thegeometrically decreasing rate of rise insures the absence of humps orother abrupt changes in curvature of the cam surface, facilitating thelocking and unlocking of the screen while, at the same time, the dangerof its vibrating loose is eliminated.

'The'wid'th of the sheet 20 and channels 2| and 22 is such that theentire assemblage overlies the sash stops M at either side of thewindowopening a minimum of inch, sufficient toprevent the entry of flyinginsects therebetween while, as-shown'and described, the upper channel 2|overlies the upper sash stop l4 and "the lower channel 22 overlies theshoulder i5; for the same purpose. The screen described thus providesadequate and efiectiveprotection against the entry of house flies,-mosquitoes and other undesirable insect life. it is .a full screencosting less than a framed screen large'enoug h taprotect "only thebottom-sash or one-half of the window. It is very easy to install and"remove, roll up and'store in the winter and does not requirepain-tingmaintenance.

Having thus described the inventio'nwhat is claimed as new and desiredto be secured by Letters Patent is:

1. A window screen comprisin a sheet of screen material approximatingthesize of the window openin to be screened, elongated clamp means securedto a margin of said sheet and adapted to besecured at -the top of awindow opening, top support means adjustable for plumb, level and heightof window, elongated clamp means secured to'the opposite margin of saidsheet, cams pivoted on said secondclamp means, and locking meansengaging said cams and adapted to be secured at the'bottom of a windowopenin and beingiad justable for plumb, level and height of :window,each said cam having a curved operative surface comprising anentering-portion withya geometrically decreasing rate of rise inverselyproportional to the" rate of tension build-up in the screen as itisbeing locked, untilit reaches zero :rise atthe locking position, thepoint of contact between camand locking devicawhen in looking positiony, being disposed directly 'beneaththe cam t, '2. Window screenaccording to cla'im'l, each said cam having a handle portion extendingsubstantiallyradiaiiy from said pivot, saidhandle portion beingsubstantially horizontal when. said loo-Icing portion of said camsurface, is in engage? in maximum tension andl'ockedl JACOB.M.,GWYNNE. I

Renee's, 'cirenf ment with said locking means, when thefscreen is Thefollowing references are of record in the file of patent:

STATES PATENTS" Number Name Date, I 1,972,539 Simpson sept. 4,:1'9342,415,200 Willett Feb. 4, '1947

